An object is kept at a distance of 100 cm from lens of power - 4 D

power 4dAnyway coming to your question the requirement of +- 4D for a job means that the eyesht of an applicant should not exceed these values that is +4D and -4D and in otherThe power of a lens is +4D. Find the focal length of this lens. An object is placed at a distance of 50 cm from the optical centre of this lens. State the nature